Westpac chief Gail Kelly has joined the chorus of bankers warning borrowers may not be so lucky after the next RBA cut.

After several days of stalling, the big banks last week passed on the full 25bp Reserve Bank cut to mortgage holders, but Kelly has told reporters this may not be the case next time the RBA moves.

Fairfax has reported that Kelly warned of the possibility of tightening credit availability as the Eurozone economy worsens, and said many funding markets used by Australian majors had "effectively closed".

"And when they open up, our estimation is that the cost of raising money will actually be more than it was at any point during the global financial crisis," Kelly said.

Kelly called Westpac's decision to pass on the full RBA cut "finely balanced", and warned that banks may only pass on a portion of future cuts.